Use this seismology calculation to reproduce a stated convention, screen observations, or compare scenarios whose units, coordinate conventions, catalog selection, and model assumptions are known.

Gap (°)

Required number in °. Largest azimuthal gap.

d_near (km)

Required number in km. Nearest station distance.

The cited overview of Seismometer supplies background for the terminology and domain context used by this tool.^[1]

Warn when the station azimuthal gap is wide enough to push hypocentres systematically into the gap. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

Biased?

Returned boolean. Whether systematic location bias is expected.

Advice

Returned string. Mitigation advice.

• Earth structure, source geometry, path effects, site response, instrument response, catalog completeness, uncertainty, and the fitted range can dominate the accuracy of simplified seismic calculations.
• Gap must be at least 0.
• d_near must be at least 0.
• Use finite inputs in the displayed units, preserve source measurements and assumptions, and independently verify consequential decisions.

For analysis or hazard decisions, retain uncertainty and provenance and compare the result with waveform processing, calibrated regional models, and guidance from qualified seismologists or the responsible agency.

• Station Gap Azimuthal Coverage Degree Calculator

  Largest azimuthal gap between consecutive stations around an epicenter.

• Wadati Residual Histogram Binner

  Bin station Wadati residuals into a fixed-width histogram with outlier tail capture.

• Bath Law Largest Aftershock Gap Note Lookup

  Båth's law: the largest aftershock sits about 1.2 magnitude units below its mainshock.